The present invention relates to an auxiliary appliance, more precisely to a mitring device, designed to set the cutting angle in mitre-cutting operations and comprising two hingedly interconnected arms, each having at least one orientation face.
In mitre-cutting, i.e. cutting of two edge pieces that meet to form a joint at a corner, a so called mitre joint, it is as a rule difficult to determine the (bevel) angle at which the ends of the edge pieces are to be cut. For example, it is often necessary to cut bevels in edgings, profile sections, pipes and the like for adaptation of the angle to bay windows and other recesses, corners to be lined with edgings and so on. In simple cases, for example in the case of right-angle cutting, fixed settings may be used, but in the case of other angles, the task often is a more complicated one. Normally, it is necessary to first measure the angle, thereafter divide it by two and then set the cutting angles in accordance with the angle indexes on a mitre crosscutting saw or similar appliance. All these steps do, however, involve considerable risks that errors occur, errors that in addition reinforce one another.
In order to reduce these sources of error it is further known from the Swedish Patent Specification 8201898-7 to provide a mitre-cutting apparatus comprising two hingedly interconnected arms and saw-guide means detachably fastened to one of the arms. The saw-guide means is arranged to ensure that the saw is guided to move at right angles to the arm on which the guide means is mounted. The two arms are provided with depending guide pins serving as auxiliary means in the sawing operation proper. Additionally, from the Swedish Patent Specification 8200065-4 is known a device for angle measuring and mitre cutting. Essentially, the device comprises two arms or wings, which are hingedly interconnected by means of a sprocket segment to ensure synchronous arm movements. The wings are provided with flanges serving as a support face, on which rest the articles to be severed or mitre-cut. In addition, the device comprises guide means to guide the tools used for the sawing operation.
Each one of these prior-art devices is however intended to measure a mitre-joint angle and to perform sawing at this angle. In consequence hereof, the devices are restricted to use with manual sawing tools. In addition, the mitring device is connected with the saw-guide means, making the devices expensive and complicated to manufacture. Also, in practice they have proved inconvenient to use.
Consequently, there is a need for a mitring device, which is simple and inexpensive both to manufacture and to use and which at the same time eliminates or at least reduces both reading and setting errors. In addition, it is desirable to be able to use the mitring device together with several different kinds of cutting tools.
One object of the present invention thus is to provide an auxiliary appliance, known as a mitring device, to set the cutting angle in mitre-cutting operations, by means of which the above drawbacks found in prior-art devices are completely or at least partly eliminated.
This object is achieved by means of a mitring device as defined in the appended claims.
The mitring device in accordance with the invention comprises two arms, which are pivotally interconnected by means of a hinge, each one of said arms having at least one orientation face, and an angle-indicating means, which is connected to the arm-interconnecting hinge via a gear mechanism, the latter being adapted, upon relative turning motion of the arms, to turn the angle-indicating means relative to the arms over a distance that essentially corresponds to half said arm-turning motion.
In this manner a simple construction is obtained, that is uncomplicated to use and in addition is inexpensive to manufacture owing to the small number of components involved. In use, the mitring device is positioned in the place where the mitre-cutting operation is to be performed and the orientation faces on the arms are set accordingly. The mitring device, still with the arms in the set position, is placed in such a manner that one of the orientation faces instead extends in alignment with the edge of the object to be cut, whereupon the cutting tool is orientated as indicated by the angle-indicating means. The operation is wholly visual, thus obviating the need for numeric angle readings, calculations and so on. Once the cutting tool is set and preferably immobilised in the set position, the mitring device is removed and the cutting operation may be performed.
The gear mechanism of the mitring device in accordance with the invention further preferably comprises a first toothed member, which is stationarily arranged on a first one of the arms, and a second toothed member, which is movably arranged on the second one of said arms and meshes with the first toothed member, the angle-indicating means being securely joined to the second toothed member. In addition, the toothed members preferably consist of gear wheels, the second, movable gear wheel comprising twice as many teeth as the first, stationary gear wheel.